[108/119] i2c: Fix userspace_device list corruption

Greg KH
2009-12-07T00:16:46Z

[-- Attachment #1: i2c-fix-userspace_device-list-corruption.patch --]
[-- Type: text/plain, Size: 2782 bytes --]

2.6.31-stable review patch. If anyone has any objections, please let us know.

------------------
From: Jean Delvare <khali@linux-fr.org>

commit bbd2d9c9198c6efd449e9d395b3eaf2d03aa3bba upstream.

Fix userspace_device list corruption. The corruption was caused by
clients not being removed when adapters with such clients were
themselves removed. Something like the following would trigger it
(assuming i2c-stub gets adapter number 3):

# modprobe i2c-stub chip_addr=0x50
# echo 24c08 0x50 > /sys/bus/i2c/devices/i2c-3/new_device
# rmmod i2c-stub
# modprobe i2c-stub chip_addr=0x50
# echo 24c08 0x50 > /sys/bus/i2c/devices/i2c-3/new_device

For the records, the stack trace in the kernel logs look like this:

kernel: WARNING: at lib/list_debug.c:30 __list_add+0x8b/0x90()
kernel: Hardware name: (...)
kernel: list_add corruption. prev->next should be next (c137fc84), but was (null). (prev=f57111b8).
kernel: Modules linked in: (...)
kernel: Pid: 4669, comm: bash Not tainted 2.6.32-rc8 #259
kernel: Call Trace:
kernel: [<c111eb8b>] ? __list_add+0x8b/0x90
kernel: [<c111eb8b>] ? __list_add+0x8b/0x90
kernel: [<c103265c>] warn_slowpath_common+0x6c/0xc0
kernel: [<c111eb8b>] ? __list_add+0x8b/0x90
kernel: [<c10326f6>] warn_slowpath_fmt+0x26/0x30
kernel: [<c111eb8b>] __list_add+0x8b/0x90
kernel: [<c11ba165>] i2c_sysfs_new_device+0x1c5/0x250
kernel: [<c10861be>] ? might_fault+0x2e/0x80
kernel: [<c11b9fa0>] ? i2c_sysfs_new_device+0x0/0x250
kernel: [<c118c625>] dev_attr_store+0x25/0x30
kernel: [<c10e305c>] sysfs_write_file+0x9c/0xf0
kernel: [<c109d35c>] vfs_write+0x9c/0x160
kernel: [<c10e2fc0>] ? sysfs_write_file+0x0/0xf0
kernel: [<c109d4dd>] sys_write+0x3d/0x70
kernel: [<c1002ed8>] sysenter_do_call+0x12/0x36

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/i2c/i2c-core.c | 11 +++++++++++
1 file changed, 11 insertions(+)

--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -718,6 +718,7 @@ int i2c_del_adapter(struct i2c_adapter *
{
int res = 0;
struct i2c_adapter *found;
+ struct i2c_client *client, *next;

/* First make sure that this adapter was ever added */
mutex_lock(&core_lock);
@@ -737,6 +738,16 @@ int i2c_del_adapter(struct i2c_adapter *
if (res)
return res;

+ /* Remove devices instantiated from sysfs */
+ list_for_each_entry_safe(client, next, &userspace_devices, detected) {
+ if (client->adapter == adap) {
+ dev_dbg(&adap->dev, "Removing %s at 0x%x\n",
+ client->name, client->addr);
+ list_del(&client->detected);
+ i2c_unregister_device(client);
+ }
+ }
+
/* Detach any active clients. This can't fail, thus we do not
checking the returned value. */
res = device_for_each_child(&adap->dev, NULL, __unregister_client);